Last week I set a conundrum: what do these photos represent? Actually, it wasn’t much of a conundrum, since Caroline got it within five minutes of my posting. I shall have to come up with some more difficult ones for my knowledgeable readers. She was correct (and others confirmed her suggestion). They are the nests of potter wasps, who regularly build in our pigeonnier.
I should explain that our pigeonnier is attached to our house and our bedroom leads into it, so its upper room acts as a small study. We were completely unaware of these creatures’ activities in there until we found some empty ‘pots’ stuck on behind the curtain. Further investigation revealed more of them attached behind books in the bookcase. We discovered yet more in a drawer, which lacks a handle and thus has a hole in it. We very rarely open that drawer, so they went undisturbed.
This year, for the first time, we have heard the young wasps breaking out of their nests. I tracked down intermittent buzzing to a cardboard box on top of the tall bookcase and, yes, there were the nests. I have yet to see one hatch out, though.
My internet researches tell me that potter wasps are the most diverse subfamily (Eumenidae, about 3,200 species) of the wasp family, Vespidae, which number about 4,500 species altogether. They also vary considerably in appearance. I haven’t been able to get a shot of ours but they are elongated and brownish in colour: quite unlike the other species of wasp around here.
Most of the potter wasps build their nests out of mud made by mixing earth with water. They are quite exquisite constructions, each one capped with a little lid. It must take a lot of work and persistence. The wasp lays one egg in each pot. To feed the resulting larva until it pupates, it collects and paralyses caterpillars and other grubs, which it immures with the egg. The adult wasp can take up to a year to emerge and then feeds on nectar. Potter wasps are usually solitary and do not live in colonies.
I had neither heard of nor seen potter wasps before we lived here. These fascinating insects don’t bother us at all, so I am inclined to leave them in peace in our pigeonnier. I do, though, take slight exception to their leaving muddy marks on my books.
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Life on La Lune 
Hi, Thanks for your interesting info. on Potter Wasps. I just found some cells behind one of my curtains (16380 Charras) and a friend in the States identified them for me via this article. Glad to hear that yours have not caused any problems. Lynn Clark
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Thanks for your comment, Lynn. We were very surprised when we found these little clay pots. But I have to say that the wasps themselves have never caused us the least problem. And they return every year! We have had them attached to curtains, like you, stuck onto book spines and inside drawers. I find the whole thing fascinating and quite remarkable. They are obviously very attached to certain places.
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They are remarkable creatures. What beautiful pots. I’ve never seen any around here; the wasps we get are common or garden!
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Interesting that you don’t get them there. Mind you, we have noticed them here only in the last few years. They are extraordinary creatures and very good at finding places where the larvae will be undisturbed.
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We have them here in Le Marche too, they call them spider wasps – and they get into everything! but amazing to watch them build a nest. Potter wasp is much more accurate I think!
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They are found widely throughout the world, I think, but I never saw any in the UK. They get into the oddest places – and you don’t find them for years afterwards.
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We’ve had masses of them this year, they particulaarly like going behind pictures. I’d heard they were completely non-agressive, then I saw a story in the Sud Ouest about someone being hospitalised after being attacked by potter wasps. They may have mistaken the wasps but I’m no longer quite so blasé about finding the nests in the house.
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They have never bothered us but perhaps, like all wasps, they become aggressive if they feel threatened. Or maybe that person was really stung by a frelon. At least they can get out of our pigeonnier easily without coming into our bedroom.
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Ah, interesting that they are in France; we have lots of them here in Tuscany and they often annoyingly get into the wardrobe and you find your the dress you were about to wear has these little muddy pots attached to it. I opened one up to find the paralysed spiders inside (quite a lot in such a tiny container), a ready, if slightly gruesome, store for the hatchlings.
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Some of my books have indelible muddy marks on them. Fortunately, they haven’t found our clothes hanging space yet. I found small grubs in one pot. It is rather gruesome but then nature is not sentimental.
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Talk about coincidence, I just found some of these behind a mirror in our gite. Mystery solved, thanks Vanessa!
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They are clever at finding places where they will not be disturbed. Glad to have solved the mystery!
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I am soooo sorry Nessa to have spoilt your conundrum by replying too early. Showing off, no doubt! I encountered these insects in Kerala, where one insisted on building on the outside of my suitcase (which was red canvas), and even though I destroyed several nests, it just started again. Maybe they came to France in someone’s luggage? It was quite a delicate creature, with longish legs, and it came back again and again with a tiny pellet of wet red mud from the river. The constructions were, as you say, exquisite. I had photos which I just can’t find.
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No, don’t worry. I did ask people to make suggestions. They are very persistent, plainly, and like to nest in the same place, hence their attachment to our pigeonnier.
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